Abrasive



June 11, 1935. J, ETz 5 A I 2,004,466

ABRAS IVE Filed April 28, 1931 INVENTORS. J s ph B. D1227; Henry L. P/ummer ATTORNEY..

'10- fabrics, heat treated drying oils and oleo resinous and at the same time shall be relatively hard.

Patented Jane 11, 1935' 2,004,466

y m- ED, STATES; PATENT OFFICE,

ABRASIVE 'Joseph B. Dietz, Lansdowne, and Henry L. Plummer, Philadelphia, Pa., a'ssignors to E. I. du Pont de Nemours 8; Company, Wilmington, Del., a corporation of Delaware Application April 28, 1931, semi No. 533,538

' 10 Claims. (01. 51-280) This invention relates to the art of abrasives and gum up'with the dust which is cut from the and more particularly it relates to articles of this surface being abraded. In wet sanding operaclass having improved compositions to hold the tions; most varnishes become soft due to the acabrasive in place on the paper or fabric base. tion of the water.

5 Various materials have been used for this pur- This invention has as an object an abrasive 6 pose, Where resistance to water is not impor-- system having an improved coating for holding taut, glue or any other water soluble binder can. the abrasive material on the base. Another obbe used to strengthen the paper and hold the ject is an improved sandpaper having a binder abrasive in place. For water resistant paper and system which shall have satisfactory flexibility varnishes have been used.. Various varnishes Another object is to improve the water andoil containing asphalt are sometimes used to give the proofness of the sandpaper. Another object is to sandpaper-a standard backing color. provide a binding material which shall be rela- Inthe manufacture of waterproof sandpaper, it tively free from gumminess and which shall not 5 is customary to apply thecoating by means of" collect the dust that is cut from the material berollers. The following system is typical: ing abraded. A further object is to provide a The paper is-co'ated on both sides in one opbinding material which dries'in a shorter time eration with what is known as a back-size and a thereby decreasing the cost of production. A still pro-size. The former consists of an emulsion of a further object resides in the method of making 30 long oil varnish containing a small quantity of our improved abrasive. water and asphalt coloring matter,-which satu- These objects are-accomplished by the followrates the paper and gives it strength, The latter ing invention, which consists in using certain oil consists of waterproof varnish sealer which serves modified poly y l o l-p lybasic acid resins as a base for the application of the-binder. The as the binding materials in one or bothof the two binder, also applied by means of a roller,is a flexilast coats in a system such as outlined above in 25 ble oleo resinous varnish. The abrasive material connection with the prior art. is sprinkled on the wet binder coat and theexccss T Single figure 0f the drawing Showing shaken oif. The finishing coat is known as a cross section of sandpaper is illustrative of the sandsizeand is applied to the abrasive material preferred embodiment of our invention. a

itself, after partial drying of binder coat contain- The numeral designates a paper base 'im- 30 ing abrasive, serving to hold the grits in place and pregnated for strength. The backsize impregna bind them firmly to the binder coat. tion, indicated by the numeral 2, is an impregnat- These materials are applied, according to the ing emulsion of long oil varnish and asphalt color.

prior practice, at a relatively high temperature, During the operation in which the backsize is I varying from 110 F. to 165 F., resulting in a thin applied. a presize consisting of a waterproof 35 coat application, due to low viscosity of the varvarnish sealer is' applied to theother side of the nish-atthe higher temperatures. Thevarnish is paper. This sealer composition not only 'imapplied at high solids content to insure 'a thin; pregnates the paper from the side applied, as ineven. coat of abrasive material and thereby-a u dicated by the numeral 3, but also may form a 40 form, more flexible sheet of sandpaper. The varthin coating on the impregnated base as desig- 40 nishes are bought by the customer at a solids c9 nated by the numeral 4. A binder coating 5 content up to 90% and thinned for application by an sisting .of .anoil modified polyhydric alcoholamount depending upon the size of the abrasive polybasic acid resin is now applied The sand, material to be bound to the paper and also upon or other abrasive, o'r polishing material 1 is then 15 the weight of the paper. sprinkled. on, .or otherwise suitably applied, to

7 There are numerous disadvantages with the the binder coating while it is still wet, The paper system of waterproof ndpaper commonly used is then baked for a short period of time. A sandas outlined above. ey sometimes lack sufll-, size coating 6, consisting of an oil modified polycient flexibility to allow the paper to conform hydric alcohol-polybasic acid resin. more fully readily to the surface on which it is used and the referred to hereinafter, is then applied over the paper cracks after it hasfbeen used for a short binder. coating 5 which has the abrasive material f time. If satisfactory in flexibility, the binder anchored or embedded therein. The product is may lack sufllcient hardness and, strength to .hold thenbaked until the desired hardness of the systhe grits firmly in place. There is also a tendency' 'tem isT-obtained. I for the binder andjsandsize to be thermo-plastic' For the finer grades of sandpaper the best re.-- 55 sults are obtained when one of the resin coatings designated by the numerals and 6 is somewhat flexible and the other coating is comprised of a hard strong resin. The methods of making polyhydric alcohol-polybasic acid resins having the desired characteristics are illustrated in the following four examples.

Example I This resin containing the equivalent of 40% glyceryl tri-phthalate, 30% China wood oil, and 30% linseed oil, may be made from the following ingredients:

Percent Phthalic anhydride 29.35 Linseed oil acids 26.60 China-wood oil acids 26.60 Glycerol (dynamite grade) 17.45

This resin solution is made as follows: The above mentioned ingredients are put into an ordinary varnish kettle and brought to a temperature of about 437 F. in about one hour. The kettle contents are held at that temperature until a 60% solution of the material in Hi-fiash naphtha (an aromatic solvent with 150-200" C. distillation range) has a viscosity of about 0 on the Gardner-Holdt scale. This takes about .three hours after reaching temperature. The kettle is then removed from the fire and 22.5 parts, by weight, of I-Ii-flash naphtha and 0.9 part, by weight, of a concentrated solution of manganese linoleate drier, are added. Before use, this solution will require the addition of further amounts of Hi-flash naphtha or other thinner, depending upon the remaining materials in the abrasive system.

Example II This resin containing the equivalent of 49% glyceryl tri-phthalate, 20% China-wood oil, and 31% linseed oil, may be made from the following ingredients:

Percent Phthalic anhydride 35.70 Linseed 011 acids--. 27.35 China-wood oil acids. 17.65 Glycerol (dynamite grade) 19.30

. from'the fire and 22.5 parts of I-Ii-fiash naphtha and .75 of the concentrated solution of manganese linoleate drier,. are added. This solution, like that of Example I, may require some further thinning before application. I

Another suitable binder system may be obtained from the resins set forth in Examples III and IV,

one resin being used as the binder coating and the The preferred binder sys-. tem from which we have secured the greatest adother as the sandsize coating as in referred to above.

Example III This resin containing the equivalent of 4% glyceryl tri-phthalate, 15% China-wood oil, and 31% linseed oil, may be made from the following ingredients:

the system Percent Phthalic anhydride 39.55 Linseed oil acids 27.50 China-wood oil acids. 13.85 Glycerol (dynamite grade) 19.10

The resin solution is prepared as follows: The

above mentioned ingredients are placed in the usual type of varnish kettle and brought to a temperature of about 437 Fain about an hour. They are held at this temperature until the acid number of the material is about 39. This takes about 4 hours at temperature. The kettle is then removed from the fire and 22.5 parts, by weight, of Hi-fiash naphtha and 0.7 part, by weight, of a concentrated solution of manganese linoleate drier, are added. This solution, like the others, may requirefurther thinning before application.

Example IV This resin containing the equivalent of 32% glyceryl tri-phthalate, 51% linseed oil, and 17% China-wood oil, may be prepared from the following ingredients:

The resin solution is made as follows: The above ingredients are placed in the usual type of varnish kettle and brought to a temperature of about 437 F. in about an hour. They are held at this temperature until the viscosity of a 67% solution in Hi-flash naphtha is G on the Gardner-Holdt scale. This requires about six hours at 437 F. The kettle is then removed from the fire and 22.5 parts, by weight, of mineral spirits and one part, by weight of a concentrated solution of manganese linoleate drier, are added. This solution is appropriately thinned in the same way as those of Examples 1, II and III.

Although the examples given above show the preparation of these resins from the drying oil acids only, they may also be prepared from the oils themselves as described in the oo-pending application of Paul Robinson, Serial No. 370,727,.

filed June 13, 1929. In this method the oil and glycerol is heated until the two phases merge into a single phase, and the glyceride so formed heated with phthalicanhydride until resinifica tion occurs. Other methods now in use for the preparation of resins of the same composition as those described in the foregoing paragraphs, are also applicable. It is to be understood, therefore, that the reference to oil modified resins in the claims is intended to include resins made as above described either with the oils or with the equivalent amount of the corresponding oil acids.

As shown by the examples, the, drying oil (the oil acids for convenience being hereinafter referred to simply as oil to indicate either the oil the other drying oil, as linseed, perilla or fish oil,"

to the degree required to produce a film having theoptimum characteristics desiredv in a binder for the abrasive material on sandpaper or similar products.

When the resins are made from'glycerol, as the polyhydric alcohol, and phthalic anhydride as the polybasic acid, the limiting quantities of the component parts of the resin expressed in terms of glyceryl tri-phthalate, China-wood oil and drying oil other than China-wood oil, may be given as follows: The more flexible component resin of the adhesive system may comprise from about 40% glyceryl tri-phthalate and 60% of mixed oils to about 32% glyceryl tri-phthalate and 68% of mixed oils. For any given amount of glyceryl tri-phthalate, the China-wood oil content may vary from about 25 to about 50% of the mixed oil. "The limits on the other component resin, which dries to the harder and somewhat less flexible film, are from the equivalents of about 55% glyceryl tri-phthalate and mixed oil to about 45% glyceryl tri-phthalate and 55% mixed oil. For any given content of glyceryl tri-phthalate, the mixed oils may contain from grades of sandpaper.

about 32.6% to about 44.4% of China-wood oil. In the case of either the binder resinor the sandsize resin, it is not necessary that the Chinawood oil vary in any particular-way with the variations in the glyceryl tri-phthalate. content as long" as it is kept within the limits specified.

-erably should be dried fora longer initial p riod for the same reason. As will be understood by those skilled in the art, glyceryl tri-phthalate as such does not exist in the resin, the mixed esters of phthalic acid and linseed oil acids being present rather than the pure glyceride of phthalic acids. Due to the difliculties encountered in determining the resin composition in terms of its actual constituents, it is more convenient to express the composition of these resins in terms ofdrying oil (or the corresponding amount of drying oil acids), and the glyceryl tri-phthalate capable of being formed by the phthalic anhydride and glycerol used in making the resin.

In. the manufacture of the coarser grades of sandpaper in which the grits range from about one thirty second of an inch to one eighth of an inch,,it is essential to use the harder drying compositions for the binder coating to. obtain the required hardness and adhesion. A hard drying resin suitable for the binding system in such paper may be comprised of about oil, consisting of from 12% linseed oil and 87 China:

wood oil to 35% linseed oil and 65%China-wood oil, the remainder of the resin consisting of' glyceryl tri-phthalate. The resin may be made by any-of. the methods previously indicated.-

Flexibility is of less importance in the coarser While it is preferredto make the resins from phthalic acid or phthalic anhydride asthe polybasic acid and glycerol as the polyhydric alcohol, it will be apparent that we may use suitable resins made with other polybasic acids and polyhydric alcohols. In making the resins with glycerol and phthalic anhydride it isdesirable in some instances to replace part of the glycerol with another polyhydric alcohol such as ethylene glycol and to replace part of the phthalic' anhydrige with'another polybasic acid such asadipic ac1 We have found that "the incorporation of any of the oxidation inhibitors commonly used in coating compositions such as creosole, guaicol, hydroquinone, eugenol, etc. into the resin coat-- ings in small amounts, as from to 1%, in-

creases the hardness and strength of either or both members of the system and makes possible the application of thicker coats than could otherwise be used. The efiect produced by the incorof the type disclosed in Examplesl and III which dry to a flexible film is of especial importance in asmuch as, the harder drying of the flexible res-. inous film which is brought about by the oxidation inhibitor makes possible the'use of a flexible coating for both the binder coating 5 and the sandsize coating 6. An abrasive system made in this manner is highly advantageous for many purposes because of the excellent flexibility coupled with high durability.

Our invention is applicable to the manufacture and production'of a paper, fabric, or other suitable basc'coatedwith abrasive materials intended for use in grinding, erations.

By the use of these oil modified polyhydric alcohol-polybasic acid resins as the binding material in the various coats of a system such as the one outlined herein, it is possible to make coated papers and fabrics which are sumciently flexible to readily conform to the surface which is being abraded or polished. The coatings possess such unusual hardness and strength that the abrasive or polishing material is held firmly in" place. This is not true to the same degree with the binders made from the rordinary type of oleo resinous varnishes unless they are baked excessively, which is injurious to the flexibility,

andlife of the sandpaper. In order to obtain a flexible coating with the previously used systems, it is necessary to bake the material in the drying operation for a long time ata relatively low temperature. If rapidity of drying is secured by raising the temperature, brittleness results. Prolonged baking of our improved compositions, has'less detrimental effect than onthose now in use. By means of the present invention, rapid drying is secured at relatively low temperatures:

making it possible to carry out the operations of manufacture in a shorter time than is required polishing, and related op- 3 for the compositions now in use. The materials oil proofness, and improved cutting power, the latter possibly due'to minimized gumminess.

The production advantage of reducing the total 20 poration of an oxidation inhibitor into the resins' As many apparently widely difiere nt embodiments of this invention may be made without departing from the spirit and scope thereof, it is v to be understood thatwe do not limit ourselves to the specific/embodiments thereof except as phthalate, approximately 50% definedain the appended claims.

We claimzj 1. A flexible sheet of abrasive material compris ing a base, abrasive material and a coating on said base comprised of a resinous mixed ester of polyhydric alcohol with polybasic acid and a mixture of fatty oil acids containing the acids of China-wood oil and the acids of a fatty oil other than China-wood oil.

2. A flexible sheet of abrasive material comprising a base, a binder coating on said base, abrasive material anchored in said binder coating, and a sandsize coating over said binder coating, one of said coatings comprising an oil modified gl'yceryl phthalate resin having a composition, when expressed in terms of drying oil and glyceryl triphthalate, of about 40% glyceryl tri-phthalate, 30% China-wood bil and 30% linseed oil, the other of said coatings comprising an oil modified glyceryl phthalate resin having a composition, when expressed in the above mentioned terms, of about 49% glyceryl tri-phthalate, 20% China-wood oil and 31% linseed'oil.

3. A flexible sheet of abrasive material comprising a base, a resin coating on said base, and a coarse grade abrasive material anchored in said coating, said resin coating comprising, when expressed in terms of drying oil and glyceryl triglyceryl triphthal'ate and 50% of a mixture of oils of which ,mixture 65% to it'l is Chinawood 011, and

the remaining 35% to 12 /2% the mixture is linseed oil.

4. A flexible sheet of abrasive material comprising a base, abrasive material, and a coating on said base comprising anantioxidant and a polyhydric alcohol-'polybasic acid resin modified with a mixture -of drying ,oils, one of which is Chinawood oil.

5. The abrasive material, set forth in claim 4 in which the resinis-a glyceryl phthalate resin..

6. A flexible sheet of abrasive material comprising a base, a binder coating on said base, a sandsize coating over said binder coating and abrasive material anchored in said binder coating, said coating comprising an oilmodified polyhydricv alcohol-polybasic acid resin, and the other of said coatings comprising an oil modified polyhydric alcohcl-polybasic acid resin containing an antioxidant. v

'7. The abrasive material set forth in claim .6 in which the resin is a glyceryl phthalate resin.

8. A flexible sheet of abrasive material comprising a base, a binder coating on said base, a sandsize coating over said binder coating and abrasive material anchored in said binder coating, each of said coatings comprising an oil modified polyhydric alcohol-polybasic acid resin containing an antioxidant. I

9. The abrasive material set forth in claim 8 in which the resin is a glyceryl phthalate resin.

10. The abrasive material set forth in claim 1 in which the'fatty oil acids other than Chinawood oil acids are linseed oil acids.

'JOSEPH B. DIETZ.

HENRY L. PLUMMER. 

